Bob has provided a starting framework for looking at maps - I think this might be split into 2 different challenges potentially and I'm also not sure if it should remain in this portal or move to evidence and interpretation. As we found in our discussions earlier, evidence and interpretation seems to be part of every challenge at some point. I guess the important question is about the main focus of the thinking.
I've added comments, questions and ideas to Bob's challenge and posted the file below: